In book I (The Object of Life) of 'Nicomachean Ethics', Aristotle sets out to determine what the concept of good represents for man and, more specifically, what the supreme good for man is. Aristotle asserts that, although there are many different relative goods that humans strive for, there is a more general absolute human good that all the relative goods can fall into, and, for Aristotle, this supreme good is happiness.
Aristotle defines good as that at which all things aim (1094a, p. 3). Furthermore, he argues that things are good in one of two ways, some things are good in themselves, while others are good for necessitating things which are good. Aristotle asserts that every form of rational activity aims at some particular end or good. Thus, since all activities are pursued for the sake of some end, or ends, by nature, must be superior to activities (line 5, p. 3). Given that every activity aims at some particular end or good, Aristotle sets himself the task of determining what the supreme good, in all activities, is for man. He bases his argument for the existence of a supreme good on the notion that, since not everything can be chosen for the sake of something else - for if they were, it would involve an infinite progression which would cause our aims to be pointless and ineffective - there must be some final end at which all humans strive towards, and this end must be the supreme good.
According to Aristotle, the supreme good must be a good towards which all humans strive and that, by itself, makes life desirable (line 15, p. 14). In other words, the supreme good must itself be self-sufficient. Furthermore, the supreme good must be a good of the soul, because it is these goods that are good in the fullest and strictest sense (line 15, p. 18). Thus, the supreme good cannot be something material, for material goods serve only as a means to some other end and can easily be taken from its possessor, and the supreme good, for Aristotle, is something proper to its possessor and not easily taken from him (lines 26-27, p. 9). So, when aiming to determine what the supreme good actually is, we must only consider those goods that pertain to the soul.
[...] Furthermore, ends such as honor and intelligence cannot be the supreme good for, Aristotle argues, the supreme good must be a good which is desirable in itself, but not something that is praised for being a good quality. The supreme good cannot be something that is praised, for praise involves reference to something else; and the supreme good must be a good that is good in and of itself, and not in relation to something else. Aristotle continues this idea by referencing Eudoxus, who says that the fact that there can be a good that is not praised for being good, but is, nevertheless, still a good, is evidence that this good is superior to all goods that are praised, because, those goods that are praised (being praised for their goodness) provide the standards to which all other goods are referred (lines 20-32, pgs. [...]
[...] For, as Aristotle suggests, the supreme good must be something towards which all humans strive for. If a final end is that which is pursued for its own sake and not just for the sake of something else, than the most final end must be that which is pursued for its own sake alone and never for the sake of anything else or for some other final end. Given that the most final end must be an end that is pursued for its own sake alone, Aristotle deduces that the most final of all ends must be happiness. [...]
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